The Common Language Runtime (CLR) Based on Mark Sapossnek Computer Science Department Metropolitan College Boston University
Agenda � What Is the CLR? � Assemblies � Execution Model
What is the CLR? The .NET Platform Clients Applications Web Form Web Service .NET Framework Protocols: HTTP, Tools: CLR HTML, XML, Visual Studio.NET, SOAP, UDDI Notepad Windows Your Internal .NET Foundation Third-Party .NET Enterprise Web Service Web Services Web Services Servers
What Is the CLR? The .NET Framework � A set of technologies for developing and using components to create: Web Forms � Web Services � Windows applications � � Supports the software lifecycle Development � Debugging � Deployment � Maintenance �
What Is the CLR? The .NET Framework VB C++ C# JScript … Visual Studio.NET Common Language Specification ASP.NET: Web Services Windows and Web Forms Forms ADO.NET: Data and XML Base Classes Common Language Runtime
What Is the CLR? Overview � The CLR provides a run-time environment that manages the execution of code and provides services that improves development, deploy- ment, and run time. � Code that targets the CLR is called managed code.
What Is the CLR? Goals � Development services � Deep cross-language interoperability � Increased productivity � Deployment services � Simple, reliable deployment � Fewer versioning problems – NO MORE ‘DLL HELL’ � Run-time services � Performance � Scalability � Availability
What Is the CLR? Goal: Simpler Development � Plumbing disappears � Metadata � Transparent proxies � Memory management � Consistent exception handling � Great WYSIWYG tool support � Designers and wizards � Debuggers � Profilers � Increased productivity
What Is the CLR? Goal: Simpler, Safer Deployment � No registration, zero-impact install � XCOPY deployment, incremental download � Side-by-side versions of shared components � Capture version at compile time � Administrative policy at run time DLL Hell � Evidence-based security policy � Based on code as well as user � Code origin (location) � Publisher (public key)
What Is the CLR? Goal: Scalability � Smart device to Web Farm � Automatic memory management � Self-configuring � Dynamically tuning � Thread pool � Asynchronous messaging � Object remoting � Events � Smart device version � Multiple RTOSes � Same tools used for desktop
What Is the CLR? Goal: Rich Web Clients, Safe Hosting � WinForms on the client � ASP.NET Web Forms on the server � Code is granted permissions � Evidence is used by policy to grant permissions � Application that starts runtime � Like Internet Explorer, IIS, SQL Server ™ , Shell � Provides some evidence � Controls code loading � Maps applications to processes
What Is the CLR? Goal: Converge Programming Models � COM, ASP, VB, C++ All services available � Many services redesigned � Ease of use � Scalability � Consistent API � � Consistent framework raises the abstraction layer � Gradual transition from simplicity to full power � Less training, greater productivity
What Is the CLR? Goal: Multiple Languages � Common Type System � Object-oriented in flavor � Procedural languages well supported � Functional languages possible � CLS guides frameworks design � Rules for wide reach � All .NET Framework functionality available � Over 15 languages investigated � Most are CLS consumers � Many are CLS extenders � Choose the right language for a particular job
What Is the CLR? Highlights � Common Type System � Mapping of data types: Programming language � Framework � Just-in-time (JIT) compilers � JIT compiles intermediate language (MSIL) into native code � Highly optimized for platform or device � Garbage collector � Permission and policy-based security � Exceptions � Threading � Reflection � Diagnostics and profiling
What Is the CLR? Services � Code management � Handling cross-language exceptions � Memory management and isolation � Interoperation between � Verification of type safety .NET Framework objects � Conversion of MSIL to and COM objects and native code Win32 DLLs � Loading and execution of � Automation of object managed code layout for late binding � Creation and � Developer services management of metadata (profiling, debugging, etc.) � Insertion and execution of security checks
What Is the CLR? Architecture Base Class Library (.NET Framework) Support Thread Support COM Marshaler Type Checker Exception Manager Security Engine Debug Engine MSIL to Native Code Garbage Compilers (JIT) Manager Collector (GC) Class Loader
What Is the CLR? Soon To Be a Standard � Microsoft, with HP and Intel, submitted proposal to ECMA to standardize: � C# � Common Language Infrastructure � Includes the Common Language Runtime and a subset of the .NET Framework classes � http://msdn.microsoft.com/net/ecma/ � http://www.ecma.ch
Agenda � What Is the CLR? � Assemblies � Execution Model � Interoperability � Security
Assemblies Overview � Contains code and metadata � Assemblies function as: � Unit of deployment � Type boundary � Security boundary � Reference scope boundary � Version boundary � Unit of side-by-side execution
Assemblies Overview � Assemblies can be: � Static: DLL, EXE � Uses existing COFF binary format � Via existing extension mechanism � Dynamic � Create assemblies with � .NET Framework SDK � Visual Studio.NET � Your own code � Dynamic assemblies
Assemblies Components of an Assembly � Manifest Metadata about the assembly itself � � Type metadata Completely describes all types defined in � an assembly � Managed code Microsoft Intermediate Language (MSIL) � Resources � For example, .bmp, .jpg �
Assemblies Components of an Assembly ParcelTracker.DLL Manifest Type Metadata MSIL Resources
Assemblies Components of an Assembly � An assembly is a logical unit, not physical � It can consist of multiple modules (.DLL, .JPG, etc.) Assembly Module In this figure, File containment implies a 1:M relationship Type
Assemblies Components of an Assembly A single-file assembly A multi-file assembly Graphic.jpg Logo.gif File2.dll File1.dll Metadata Resource Resource Manifest MSIL Metadata MSIL File3.dll Manifest
Assemblies Assembly Generation Tool: al.exe al.exe � Takes one or more files (containing either MSIL or resource files) and produces a file with an assembly manifest. � When compiling a C# file, you can specify that it create a module instead of an assembly by using /target:module .
Assemblies Manifest � Manifest contains: � Identity information � Name, version number, culture, strong name � List of files in the assembly � Map of assembly types to files � Dependencies � Other assemblies used by this assembly � Exported types � Security permissions needed to run
Assemblies Manifest and Metadata Type Descriptions Name Version Culture Manifest Other assemblies Security Permissions Exported Types Assembly Description Classes Base classes Metadata Implemented interfaces Data members Methods
Assemblies What’s In the Metadata � Description of types � Name, visibility, base class, interfaces implemented � Members � methods, fields, properties, events, nested types � Attributes � User-defined � Compiler-defined � Framework-defined
Assemblies Demo: ILDASM.EXE � Allows you to inspect the metadata and disassembled IL code in an assembly � Great way to see what’s really going on � Use ildasm /? to see the various options
Assemblies Metadata � Key to simpler programming model � Generated automatically � Stored with code in executable file (.dll or .exe)
Assemblies Metadata: Creation and Use Reflection Source Serialization Code (e.g. SOAP) Designers Compiler Other Compiler Debugger Assembly (Manifest, Type Browser Profiler metadata and code) Schema Proxy Generator Generator XML encoding (WSDL)
Assemblies Compilers Use Metadata � For cross-language data type import � Emit metadata with output code � Describe types defined and used � Record external assemblies referenced � Record version information � Custom attributes can be used � Obsolete � CLS compliance � Compiled for debugging � Language-specific markers
Assemblies Other Tools Use Metadata � Designer behavior � Controlled by user-supplied attributes � Category � Description � Designer extensibility � User-supplied attributes specify code to use � Type converters � Editors � Web methods marked by custom attribute � Type viewer
Assemblies Global Assembly Cache � A set of assemblies that can be referenced by any application on a machine � Should be used only when needed � Private assemblies are preferred � Located at %SystemRoot%\assembly � ( c:\winnt\assembly ) � Add assemblies by � Installer program � gacutil.exe � Windows Explorer � Assembly Cache Viewer ( shfusion.dll ) is a shell extension for GAC that is installed with the .NET Framework SDK � .NET Framework Configuration Tool ( mscorcfg.msc ) � Assembly must have a strong name
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